A procedure for separation of isozymes of phenylalanine hydroxylase by column chromatography will be selected. The pattern of isozymes in fetal monkey liver will be compared to that of adult monkey liver to determine if they are the same or different proteins. Search will be made for inbred strains of mice with high and low activities of phenylalanine hydroxylase in order to study the mechanism of genetic control of production of the enzyme. A study of the evolutionary characteristics of phenylalanine hydroxylase will be carried out in other vertebrate classes as well as in other representative mammals. BIBLIOGRAPHIC REFERENCES: H. K. Berry. Hyperphenylalaninemias and Tyrosinemias. In "Clinics in Perinatology", Symposium on Early Detection and Management of Inborn Errors. M. G. Ampola, Editor, W. B. Saunders Co., Philadelphia, March, 1976. Helen K. Berry and Inna B. Poncet. Collagen Metabolism and Its Relation to Hypertrophic Scars. In "Ultrastructure of Collagen", J. J. Longacre, Editor, Charles C. Thomas, Springfield, Ill. 1976, pp 169-174.